Definition of Oak ridges moraine

The Oak Ridges Moraine is an ecologically sensitive geological landform in south central Ontario, Canada. The moraine covers a geographic area of 1,900 square kilometres between Caledon and Rice Lake, near Peterborough. One of the most significant landforms in southern Ontario, the moraine gets its name from the rolling hills and river valleys extending 160 km from the Niagara Escarpment east to Rice Lake. It was formed 12,000 years ago by advancing and retreating glaciers (see geological origins, below). The moraine is currently a contested site in Ontario, since it stands in the path of major urban development (see political action).